A passenger cabin of a vehicle may be heated and cooled via a heat pump. The heat pump may use a heat pump heat exchanger external to the passenger compartment as an evaporator in a passenger cabin heating mode. The heat pump may use the same heat pump heat exchanger as a condenser in a passenger compartment cooling mode. The heat pump heat exchanger is placed in an ambient air flow path to extract or reject heat to or from ambient air. However, the vehicle may also include other heat exchangers that use ambient air to reject heat from the vehicle. For example, if the vehicle includes an engine, the vehicle may include an engine radiator and a transmission cooler. The heat pump heat exchanger may be placed in the same air flow path as other vehicle heat exchangers due to vehicle packaging requirements. If the heat pump heat exchanger is placed in front of other vehicle heat exchangers, the heat pump heat exchanger may extract less heat from air flowing in the air flow path during a passenger cabin heating mode than is desired since the heat pump heat exchanger is exposed only to ambient air. However, if the heat pump heat exchanger is placed behind other vehicle heat exchangers, the heat pump heat exchanger may reject less heat to air flowing in the air flow path since other vehicle heat exchangers may increase the temperature of air flowing across the heat pump heat exchanger. Consequently, the heat pump may not operate with as high as an efficiency as is desired.
The inventor herein has recognized the above-mentioned disadvantages and has developed a method for operating a vehicle climate control system, comprising: transferring thermal energy from a heat pump to a high temperature coolant loop in a first climate control mode; and transferring thermal energy from the heat pump to a low temperature coolant loop in a second climate control mode.
By transferring thermal energy to a high temperature coolant loop in a first climate control mode and transferring thermal energy to a low temperature coolant loop in a second climate control mode, it may be possible to provide the technical result of improving heat pump efficiency since thermal energy may be transferred to two different heat exchangers. In particular, during a passenger cabin heating mode, thermal energy extracted from ambient air via an external heat exchanger may be directed to a high temperature coolant loop where the thermal energy may be transferred to the passenger cabin. On the other hand, during a passenger cabin cooling mode, thermal energy from the passenger cabin may be transferred to a low temperature coolant loop and a low temperature radiator. Thus, two heat pump operating modes may utilize different heat exchangers having different packaging locations that may improve the heat pump's efficiency. For example, the low temperature radiator may be positioned in front of other engine heat exchangers so that it may reject more heat to ambient air during a passenger cabin cooling mode. The external heat exchanger may be positioned behind other vehicle heat exchangers so as to improve the heat pump's efficiency during a passenger cabin heating mode.
The present description may provide several advantages. In particular, the approach may allow heat pump heat exchangers to be positioned such that heat pump efficiency may be improved. Further, the approach may allow the vehicle's climate control system to operate as desired using less refrigerant. Additionally, it may be possible to reduce the size of the heat pump's external heat exchanger.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.